Directional electric tachometer including means for producing asymmetrical pulses

Claim 1

A TACHOMETER FOR INDICATING THE DIRECTION OF ROTATION AND FOR MEASURING THE SPEED OF A ROTATING SHAFT, COMPRISING A ROTATABLE MEMBER COUPLED TO SAID SHAFT AND HAVING A PLURALITY OF TEETH COMPOSED OF MAGNETIC MATERIAL LOCATED ABOUT THE PERIPHERY THEREOF, SAID TEETH HAVING A FIRST EDGE WHICH DIVERGES SHARPLY FROM THE SURFACE OF SAID ROTATABLE MEMBER AND A SECOND EDGE WHICH DIVERGES MORE GRADUALLY FROM SAID SURFACE, A COIL POSITIONED ADJACENT THE PERIPHERY OF SAID ROTATABLE MEMBER IN MAGNETIC COUPLING RELATIONSHIP WITH SAID TEETH THEREBY TO INDUCE VOLTAGE PULSES THEREIN HAVING A NON-SYMMETRICAL WAVE FORM AND NEGATIVE AND POSITIVE EXCURSIONS OF DIFFERENT AMPLITUDE VALUE, THE POLARITY OF THE GREATER AMPLITUDE EXCURSION BEING DETERMINED BY THE DIRECTION OF ROTATION OF SAID SHAFT, AND INDICATING MEANS COUPLED TO SAID COIL COMPRISING MEANS FOR CONVERTING SAID VOLTAGE PULSES INTO A DIRECT CURRENT VOLTAGE HAVING A POLARITY DETERMINED BY THE POLARITY OF THE GREATER AMPLITUDE EXCURSION.